The passage of California Proposition 1A (2008) set in motion a complete reconstruction of the railroad between San Jose and San Francisco. This blog exists to discuss compatibility between HSR and Caltrain, integration issues, and the impact on adjoining communities.

29 July 2009

Threading the San Mateo Narrows

Downtown San Mateo as previously discussed is one of the most difficult bottlenecks on the peninsula corridor, with some of the narrowest right of way anywhere on the peninsula (see mini map at right, extracted from Milepost 17 map). The following is an expanded discussion of horizontal alignment options in the downtown area.

Assuming one needs to build four tracks through this area (an assumption we will later revisit), the inescapable mathematics of right of way width and track clearances dictates that the railroad will expand significantly beyond its current boundaries. The figure below shows a cross-section elevation at Third Avenue looking "north". The building on the left is the cinema, built partially on former railroad right-of-way and completed in 2003. To the right is Railroad Avenue, providing access to several blocks of downtown business frontage. Railroad Ave becomes a residential street north of the train depot.

The cinema, along with other recently built projects such as the Main Street Parking Garage and the new train depot, have greatly restricted horizontal alignment options for the railroad. While they would only cost a few million to tear down and redevelop, these buildings are the source of considerable civic pride, so it is likely that the city will bend over backwards to preserve them--potentially at many millions of dollars of additional cost to the high speed rail project, and possibly with additional impact to residences in North Central San Mateo. Such is the sad reality of cost-benefit analysis when other people's money is involved.

The figure below shows the city's preferred vertical alignment, with the tracks relocated below grade in a four-track trench, with side clearances appropriate for safe 125 mph (200 km/h) operation. The avenues would cross the tracks on bridges.

As is readily observable, a four-track trench (the narrowest possible below-grade solution) could not be built without impacting structures on one side or the other of the right of way. Constructing the side walls of the trench would require even greater clearances than shown, approximately 110 feet by the city's own estimates--to accommodate wall tie-backs as well as temporary tracks to keep Caltrain operating during construction. More importantly, the trench obliterates Railroad Avenue, the only access to several businesses and residences. Those would have to be acquired under eminent domain.

An outright tunnel would allow continued access to Railroad Avenue, along with exciting new land uses on top of the tunnel. However, a tunnel isn't just a trench with a lid: it requires a vertical divider for fire safety and to support the roof, which further increases the side clearances. (The reasoning behind the resulting dimensions was discussed in the Joy of Tunnels.) Building an underground station would consume even more space for platforms, stairs, escalators and elevators, as will be shown later. The figure below shows how a tunnel compares to the available space: it simply won't fit without causing even greater impact than a trench.

About the only option that is possible to construct (a) without "taking" several buildings and (b) without permanently removing Railroad Avenue and its frontage is an elevated viaduct. The diagram below shows what such an elevated might look like. It could be built in halves, in order to keep Caltrain operating during construction. While an adorable little sketch by city staff (reproduced at right) shows a single concrete column supporting the entire four-track bridge deck, it is likely that seismic codes and the requirement to support massive freight trains would lead to four rows of columns, placed directly under each track. Parking is probably the only reasonable use for the concrete forest resulting underneath. The ambiance would be just like other parking garages in downtown--and might even replace other parking structures entirely, freeing up those locations for redevelopment. Driveway access to Railroad Ave businesses could be preserved.

The elevated option is also likely to be far cheaper to build than a trench or tunnel: it involves about the same amount of concrete, but far less earth moving or road closure logistics. Furthermore, an elevated does not require the permanent closure of several residential cross-streets north of downtown, as contemplated in Focus on San Mateo. Despite the visual blight and noise, look for this alternative to be ultimately favored by the California High Speed Rail Authority... and possibly also by the city, once all the trade-offs are fully understood. While the elevated may not be a desirable solution, on the whole it may be the best solution.

Station Placement

The foregoing musings do not take into account the configuration of the downtown San Mateo train station. By far the most important consideration is the location of Caltrain platforms--both their location with respect to the tracks (outside platforms vs. island platform), as well as their location along the tracks. Recall that the new depot was squirreled away to the north of First Avenue, on the outskirts of downtown, to minimize the impact of lowered grade crossing gates on rush hour traffic. If the tracks are grade-separated and grade crossings are eliminated, this concern evaporates, enabling some options for a more centrally located station closer to 3rd and 4th Avenues, which form the main east-west artery of downtown San Mateo. Such central locations would be far more accessible for both pedestrians and motorists.

In a four-track scenario, the resulting station widths are shown in the diagram below, not including the width of any ramps, stairs or escalators that might be required to access the platforms. These widths bear a direct relationship to the horizontal alignment of the tracks, since the station will be constrained on at least one side by existing structures.

The island platform requires about 6 feet more width than the outside platforms, and the tracks sit 23 feet further apart. The CHSRA might use this as an excuse not to implement island platforms, despite their significant operational advantages.

Let us consider the below-grade option favored by the city, with the station remaining at its current 1st Avenue location. The existing station is shown below in a cross section at 1st Avenue looking "north":

A below-grade station would be built in a trench, with 1st Avenue on an overpass. For all the talk about San Francisco's Transbay "train box", San Mateo's very own train box would be nothing to sneeze at, as readily observed in the following diagram.

Whatever horizontal and vertical location is ultimately selected, none of these four-track station options will fit in downtown San Mateo without very significant property impacts. So you might consider...

Solutions with Three Tracks

So far, we have assumed that four tracks would be absolutely necessary throughout downtown San Mateo, with potential property impacts that go along with that. In practice and with a little bit of creativity, the envisioned levels of Caltrain and HSR service could be achieved on just three tracks, by consolidating the two southbound tracks for a brief stretch through downtown. The goals of such an approach are:

To reduce the property impacts to downtown businesses and residents by minimizing excursions outside the existing right-of-way

To increase the range of configuration options for the downtown Caltrain station, for example an island platform that maximizes station access from 3rd and 4th Avenues

To reduce property impacts along the narrow right of way in the North Central neighborhood, immediately to the north, such that residences do not have their driveway under an elevated.

Naturally, such real-world engineering involves compromise. The drawback is that local and express trains must all share the same southbound track through downtown. Scheduling trains around this operational constraint involves coordinated HSR and Caltrain timetables, which can probably be done reliably because all southbound trains originate from nearby San Francisco and are unlikely to build up significant delays in the space of just 17 miles. (The northbound tracks do not benefit from this proximity to a terminal, and would be difficult if not impossible to schedule reliably; for example, a delay in Bakersfield could later result in a northbound conflict at San Mateo. That's why two northbound tracks are still required.)

Two of the most interesting three-track configuration options are shown in the figure below (linked to annotated PDF file), as designed by Richard Mlynarik. Both assume an elevated, for the reasons described above, and stay confined to the existing right of way between Monte Diablo Ave and the San Mateo Creek to reduce impact to residences along those blocks. There may be more design options with three tracks, but these two convey what is possible.Option 1 is a three-track station with outside platforms. This can be built either just north of the parking garage and cinema, at the existing location of the San Mateo station, or just south of the offending buildings. The southbound track skirts the cinema as tightly as possible. The northbound platform is built over Railroad Ave, which complicates access by ramps, stairs, escalators or elevators. Railroad Ave would have to be shifted underneath the elevated to free up room under the platform, and station access might interfere with business frontage.

Option 2 is a better three-track station with a central island platform built over Third and Fourth Avenues. The same layout from the PDF file is overlaid on an aerial photo below.

The central island platform enjoys easier access from below, since stairs and elevators would have ample space to touch down under the elevated, with direct pedestrian access from both sidewalks of 3rd and 4th Avenues. It doesn't have to be an oppressive structure: it could look like this amazing photo of Amsterdam's Bijlmer station, a model of pedestrian access.

The difficulties in downtown San Mateo will be great, but so is the potential for an elegant solution that better integrates the station with the city.

32 comments:

Well what may be an option..as CAHSR proposes down in OrangeCoand what just might have to happen here is the HSR tracks will be in a tunnel..only Caltrain remains at grade.This of course will bring no grade seperation..and this is what the nimbys in PA may also see.Of course this will be costly but there may be no other choice

Mlynarik's solution is great but... won't this mean that local trains can't stop at San Mateo? Remember, the express trains will be on the outer tracks in his preferred plan. Which is pretty much the problem: his suggestions are inconsistent with each other.

A two-level elevated would be extremely tall. This isn't BART or the New York Subway, it's grand ole' American style oversize heavy freight. (oh and HSR and Caltrain, by the way).

As for an HSR tunnel with Caltrain remaining at grade, that is inconsistent with city policy, Caltrain policy, and the CPUC probably won't stand for it (they being the state regulatory authority on grade crossing / grade separation matters)

So two-over-two would be realistic if you could talk UP into dropping its freight service on the Peninsula corridor? What are the clearance differences between a double-stack freight car and an HSR trainset?

Double stack freight trains havea max height of 20'3" above top of rail, Caltrain is I believe 16', while HSR (and other single-level) trainsets typically have a height of something like 13'6" with the pantograph locked down.

By the way, everyone is ignoring the obvious solution: knock down the cinema and parking garage, and use a tighter track spacing so that you can fit four tracks into 60 feet and never mind the "will not clear man on side of car" issue. Somebody from this blog REALLY needs to go out to Attleboro with a tape measure and find out what the REAL track spacing is on a REAL 125 mph line in the US, with US clearances and US freight trains. And then lobby the CPUC until they allow that.

I think a above grade with a column for each track is a little much for lightweight European Passenger trains. Maybe if it was a freight Only corridor, then yes. But, I think we can keep the concrete column jungle to a minimum at a column per two tracks.

The space underneath will be able to serve for MORE than parking. Perhaps it can be a mix of parking with bicycle/pedestrian trails, minor landscaping. I don't think that pure parking would make the tracks above look very eye appealing, Maybe 50/50.

Another thing would be to decorate the column's and surrounding building's with very attractive designs for pedestrians/bicyclist's.

arcady wrote "everyone is ignoring the obvious solution: knock down the cinema and parking garage"

No they're not. The article explicitly notes that this obvious solution isn't likely to happen.

Besides which, then what happens on the width constricted curve north of downtown San Mateo?

Spend some time with a map and a ruler -- things aren't as obvious as they may superficially appear.

"and use a tighter track spacing so that you can fit four tracks into 60 feet and never mind the "will not clear man on side of car" issue."

Side clearances from high speed rail traffic have nothing to do with that aspect of 19th century US/Californian legislation.

If you look at the legal requirements and the construction standards for new and rebuilt lines pretty much anywhere in the first world, you'll not find side clearances and inter-track spacing significantly less than the what's shown here.

Furthermore, just what are the odds of an agency like the FRA -- or local fire departments for that matter -- allowing anything cheaper and less hypothetically "safe" than blue helmeted one world government bureaucrats in Brussels (or Berlin or Oslo or Seoul or Rome) do?

Structures simply aren't going to be allowed to be built the way they were 20 or 100 years ago, sorry. Just compare pretty much any new tunnel with those built even 15 years ago. Passenger evacuation, fire safety, and derailment containment requirements are only going to more stringent.

"Somebody from this blog REALLY needs to go out to Attleboro with a tape measure and find out what the REAL track spacing is on a REAL 125 mph line in the US, with US clearances and US freight trains. And then lobby the CPUC until they allow that."

People from this blog -- including ones who've actually visited the Caltrain ROW other than in Google Earth -- have spent decades in the Boston area. People with names like "Clem", just for example.

Finally, I'll take German (or Swedish, or Japanese, or Spanish, or Korean, or ...) civil engineering and safety standards over "REAL 125 mph line in the US" any day -- the aim, after all, is to end up with something that works, not the glug-glug-glugging noise of the North East Corridor Improvement Project. (Less cost-effective and far worse under-delivering than the UK WCML fiasco, which is saying a lot!)

When it comes to passenger rail enginering, the contemporary US way is always the wrong way. There are no known exceptions.

PS Speaking of moronic building placement, San Mateo has no monopoly on this, and the insanity is continuing even as we speak here: San Jose has plans to build a baseball stadium on land which is obviously needed for an expanded station footprint, and of course San Francisco is "designing" a Transbay Terminal that puts the structural supports for a worthless aerial park right where trains need to run.

I have indeed read the analysis of alternatives for Orange County and thought it irrelevant to San Mateo. This document envisions solutions in constricted rights of way involving 2 + 2 stacking of the tracks. The alternatives include:

(1) the tracks in Orange County carry less than half as many trains as Caltrain(2) grade separation of Caltrain is a stated policy in San Mateo, where a dense cluster of busy thoroughfares cross the tracks(3) as covered in Focus on San Mateo, and as identified by the city, downtown property impacts would be extreme in any grade separation scenario that leaves the tracks (any tracks!) at grade(4) the only stacked alternative that would potentially work, a 2 track tunnel with a 2 track elevated on top, carries all the drawbacks of both options (visual blight, noise, construction disruption, permanent road closures, etc.) and would have far worse impacts than simply expanding the ROW. Even if that meant the exercise of eminent domain.

While every effort should be made to stay within the existing ROW, one still needs to keep track of the big picture, weighing the relative impacts of each solution. In my opinion none of the stacked solutions result in lower impacts than the solutions described in this blog post.

@dave: yes, aerials with 1 column for 2 tracks would work for HSR. They would probably not work for heavy US style freight, which is a big design driver on the peninsula.

@arcady: heritage PRR / New Haven dimensions won't cut it in the 21st century. It's one thing to be grandfathered in, and quite another to start essentially from scratch.

the only stacked alternative that would potentially work, a 2 track tunnel with a 2 track elevated on top, carries all the drawbacks of both options (visual blight, noise, construction disruption, permanent road closures, etc.) and would have far worse impacts than simply expanding the ROW. Even if that meant the exercise of eminent domain

If they are digging a hole for a two track tunnel ( I'm assuming cut and cover ) how much more expensive is it to dig a deeper hole, two tracks wide and two tracks deep? Not unheard of, the longest example I can think of is the subway line under Central Park West. Or the 63rd Street Tunnel under the East River. . . not that they have room for a tunnel two tracks wide.

Afaik, there is no legal requirement for all four tracks to be at the same elevation. Just out of curiosity, would it be possible to construct the following in San Mateo?

a) an aerial structure for two HSR tracks, supported by a single row of 5'4" columns, plus

b) a pair of single-track trenches to either side of them for Caltrain/UPRR and side platforms for Caltrain. If these are well ventilated and, UPRR agrees to deploy only EPA Tier 4 locomotives in the SF peninsula, the trenches could be covered with road lanes to retain the vehicular access afforded by the frontage road.

The math works out such that the foundation for the columns would be an embankment 15'4" wide, retained by 3' walls to either side of that. That would leave ample space for shaded parking and U-turn lanes under the aerial, in-between the columns.

Admittedly, there are some pretty huge disadvantages to this:

1) there are multiple gravity-drained conduits that cross the ROW in San Mateo. Trenching would require reliable diversions for them, even in the event of poor maintenance or an earthquake.

2) freight trains are limited to ~1% gradient, so bringing four tracks back to the same level (e.g. grade) might force the closure of several existing grade crossings north and/or south of downtown San Mateo.

3) the concept is virtually guaranteed to be a lot more expensive than tearing down the cinema and rebuilding it, e.g. as part of a mall/entertainment complex integrated with the station (cp. Utrecht in the Netherlands, which already has one east of the tracks and is looking to expand it west of there). As they say in mathematics: if you want to solve a problem, complexify it.

NOTE: in theory, it would also be possible to put HSR underground and run Caltrain locals + UPRR on the aerial structures. However, as you point out, the great weight of the freight trains would likely require the use of a row of columns underneath each track (possibly arranged in a zig-zag pattern).

The underground tracks would then be locate closer to the abutting buildings, possibly leading to greater vibration impacts on their foundation slabs. On the other hand, HSR trains require less vertical clearance than AAR plate H freight trains, so the trenches could be a few feet shallower.

Engineering is supposed to be about developing solutions that address identifiable problems in an effective fashion.

Stating with a "solution" – better described as a "slogan" or a "mantra" or an "obfuscation" — and then working backwards to try to state a problem that it "solves" is a guarantee of failure.

"There must be four or more tracks everywhere between San Jose and San Francisco" is a solution in search of a problem.

"All trains must run via San Jose" is a solution in search of a problem.

"Freight trains must run to San Francisco" is a solution in search of a problem.

"San Francisco needs two separate terminal stations" is a solution in search of a problem.

"San Jose needs a two level station and 14 platform tracks" is a solution in search of a problem.

"San Jose to San Francisco needs to accommodate 12 high speed trains per direction per hour and 12 Caltrains per direction per hour" is a solution in search of a problem.

"Terminal stations need tail tracks" is a solution in search of a problem, and a solution remarkably similar in relevance and effectiveness to "terminal stations need turntables and coal loading yards."

NONE of the above have anything to do with solving any real world transportation problem on the San Francisco Peninsula.

If you're asking how to stack four tracks vertically in downtown San Mateo you're just not thinking about addressing a real problem; you're just reciting a mantra.

Caltrain and HSR both want to use modern 25kV AC electrification. UPRR could deploy an electric locomotive for its Mission Bay Hauler between south SF and Santa Clara but it would have to switch to diesel-electric traction for the last section to Fremont as well as the freight spurs to its customers.

It's not possible to just add a pantograph to a legacy diesel locomotive because 25kV systems need a large transformer to bring the voltage down to the 1500-3000V range the stator windings in the electric motors can handle. Deploying both an electric and a diesel engine or, switching between them, would entail capital investments and operational overheads that UPRR won't be prepared to pay for.

Gradually upgrading its fleet to EPA Tier 4, on the other hand, is mandatory. However, since the new standard applies only to new and replacement engines, someone would still need to persuade UPRR to meet the new standard in the Bay Area earlier than elsewhere.

@ anon @ 12:30 -

we're not trying to solve only the strictly regional transportation issues in the SF peninsula. We're looking for technical solutions for full grade separation for Caltrain, UPRR and the starter line for a brand-new HSR network for the state.

You may not perceive HSR as a requirement, but a majority of California voters did when they approved prop 1A(2008) last November - after Wall Street went into a tailspin.

HSR isn't a solution in search of an existing transportation problem. Rather, it's a solution to a problem we know we're going to have in the foreseeable future. Caltrain, too, will become a problem for cross traffic before long unless grade crossings are eliminated. The train box underneath the new SF Transbay Terminal will boost ridership on both Caltrain and HSR.

You're in denial about all that. Building the HSR starter line now and along the Caltrain ROW is actually an example of proactive transportation planning.

diesel trains can operate in tunnels if there is sufficient ventilation, especially at platforms where passengers may be waiting. One simple option is to simply not cover them up and install a highly available system of fans to vent the exhaust gases released by the locomotives as they pass by. The mass flow through the fans would need to be high enough to dilute the gas released near the surface to safe CO2 concentrations.

Of course, if the subway tunnels were used for HSR rather than Caltrain + UPRR, the Caltrain platforms would be on the aerial rather than underground. There are no plans for an HSR station in San Mateo.

Scheduling trains around this operational constraint involves coordinated HSR and Caltrain timetables, which can probably be done reliably because all southbound trains originate from nearby San Francisco and are unlikely to build up significant delays in the space of just 17 miles.

The assumes trains are departing out of TBT on-time. I would not make that assumption. Of course, we will have to see how the final "terminus" layout comes out, but based on what has already been discussed earlier in this blog, it is probably safe to assume that TBT track layout will be less than optimal and thus we can expect delays getting in and out of SF.

My local BART station is 8 miles from a terminus, and experiences frequent delays during commute hour. Granted, BART is extremely susceptible to systemwide delays, but given that CAHSR seems to be following BART design principles, it is not totally apples-and-oranges.

It would be much cheaper than elaborate systems executed in concrete, rebar and ventilation to accommodate a few trains a day. NJTransit is buying fancy ALP46s for 8 million a pop. CAHSR could give UP 3 of them, ( not that ALP46s are appropriate for freight ) two out on the line and one in the shop, for 24 million. How does that compare to contorting things so 3 diesels a day can wander through?

it would have to switch to diesel-electric traction for the last section to Fremont as well as the freight spurs to its customers.

The Baltimore and Ohio began to do it in 1895 in Baltimore, though they were dealing with steam not diesel. The Pennsylvania Rail Road had an extensive system that survived until recently. There are solutions to the problems.

It's not possible to just add a pantograph to a legacy diesel . . .

I'm sure it could be done given enough time and money. Why would anyone want to do that?

UP regularly replaces locomotives. New electric locomotives are manufactured, no need to go salvaging a diesel to make one.

.... 25kV systems need a large transformer to bring the voltage down to the 1500-3000V range the stator windings in the electric motors can handle..

What does the pantograph have to do with the transformer other than they are connected electrically?

Transformers are large. The electronics to convert whatever is coming in on the pantograph or third rail to the 3 phase power modern equipment uses takes up a lot of space. Both weigh a lot. Diesel engines, generators and fuel tanks that can hold thousands of gallons of fuel take up a lot of space and weigh a lot. More than transformers and inverters. Or do you have some other point?

Deploying both an electric and a diesel engine or, switching between them, would entail capital investments and operational overheads that UPRR won't be prepared to pay for.

Then maybe it's time to find a short line operator who can cope with the 3 trains freight trains a day the Peninsula generates and those new fangled electric locomotives that have been in use since 1895. It's not like the backwater branch on the Peninsula is making or breaking UP's bottom line.

Re the sky falling with fewer than four parallel tracks everywhere from Anaheim to San Francisco:

"Scheduling" (an entirely foreign concept to rent-seeking US professional rail consultants, but one which can and does result in hundreds of millions of dollars of cost savings elsewhere in the world) is what you use to ensure that four trains aren't in downtown San Mateo at the same time, nor that they'd be there if any combination of them are a running minute or two slowly. (This being "schedule robustness" another strange, foreign term with no translation into American English.)

That's trivial to arrange.

It's also simple to arrange that three trains aren't normally present simultaneously, meaning that there's an entire shiny, extra-expensive track just sitting around idle in San Mateo 24 hours of every day just in case, and that something would have to be really haywire for this terrible "constriction" to cause any knock-on effect. Belt and suspenders.

And what's would be that worst case? What happens if four trains do end up wanting to be in the same place at the same time? It's that one of three trains -- the fact that there's such a free choice itself shows the system is unusually robust -- might end up incurring a three minute delay. The sky has fallen and can't get up!

In other words, solve the problem of accommodating a realistic level of realistically spaced traffic operated according to realistic practices, rather than blindingly reciting the slogan "four tracks good" while pouring as much concrete as physically possible.

Why does the "solution" always have to be to spend more money on more nose bleed expensive and intrusive and under-utilized infrastructure, rather than to spend a much smaller amount of money on planning, operations and maintenance? (Yes, I know, I know...) In short, why no analysis?

Note that Caltrain, if it weren't stuck somewhere in the 19th century, could be operated robustly at its present anaemic traffic level on a single track line with a handful of intermediate passing loops ending in three track (not 8 track, not 14) terminii. This stuff isn't rocket science -- somebody just has to care. People don't understand how much capacity is lying around unused, and how much track and rolling stock and crew time and yard space is simply wasted by appalling operating practices.

Note also that if the rational and ethical and non-corrupt thing had done and four tracks had been built by sending two via Dumbarton-Altamont and two via Palo Alto, rather than all four via Palo Alto with the result of too many HSR trains with too many empty seats eating up capacity running to SJ-SF-SJ, then there would have been no need for more than 2 tracks though San Mateo.

Work smarter, not harder.

PS Here are two examples of 3 tracks designed around and operated according to a "schedule".

@ Richard - I'm not an industry insider, but it's my understanding that the complete lack of precise scheduling in the US rail industry is due entirely to the freight railroads' absolute refusal to adhere to any such schedule.

In Japan, at least, and I suspect in most of Europe as well, freight trains must follow just as exact of a schedule as passenger trains. There is no way Japanese railroads could operate under the scheduling tolerances that they do under such circumstances. Shinkansen movements are reportedly choreographed down to 15 second precision.

Basically, the US freight railroads say: "We could send a freight train down the line at any time and stop it anywhere we want for as long as we want. If that's a problem, then YOU pay to add a second track. And even then, we won't guarantee that there won't be a second freight train moving down the line in the same place at exactly the same time, and if THAT'S a problem, then YOU pay for a third track."

If both Caltrain and CAHSR do not interact with freights at any point on their routes, though, then this high precision maximal utilization of schedules should be possible.

Re: "San Mateo lies north of Redwood Junction and the Altamont / Pacheco situation would make no material difference to San Mateo."

Pacheco is an operational disaster because it will result in too many foreign trains with far too many empty seats spending too long eating up capacity on the Caltrain line. (And if anybody isn't planning for the major benefit of majority users of the line, namely Caltrain passengers, and feels that flight level zero airlines deserve absolute priority, then there's nothing we have to say to each other. Exhibit 1: Transbay JPA losers.)

Short version: if 33% or 50% of HSR trains ran Central-Valley-Livermore-Fremont-San Jose and never interfered with Caltrain operations anywhere but at the platforms in San Jose we'd have hugely reduced operational problems and massively reduced problems corridor-wide, including north of Redwood City.

We're dealing with two very different classes of traffic and service here -- regional Caltrain and inter-regional HSR -- which are forced to use shared facilities out of economic necessity, as an engineering compromise. The less they get in each others way they fewer the operational (= delay) for both of them -- this is why HS lines everywhere in the entire world apart from SJ-SF separate from regional tracks ASAP -- and the lower the massive capital costs of attempting to ameliorate and minimize the consequences of those traffic interactions (= extra tracks, extra interlockings, larger stations = $$$$$$$$$$$$$$$).

Cumulative system delays grow faster than than linearly in the number of conflict points; getting HSR out of the way at the first opportunity (Redwood Junction) not only halves the length of track over which it and Caltrain are forced to duke it out, but reduces the types of and magnitudes of conflict even more, as I might go into in a longer missive.

The less HSR and Caltrain see of each other the more reliably each will operate. This translates directly into less expensive infrastructure and less redundant, including in San Mateo.

30% more HS trains over 100% more Caltrain line translate into vastly more pain and cost, and in places we don't need it.

Re "industry insiders": you have to understand that the class of people we have designing rail service in this county have experience largely with freight (not being able to operate according to a schedule is a cultural norm); that those passenger systems we have operate at truly frightening levels of consultant, management, crew, equipment and infrastructure feather-bedding (these are cultural norms, as public transportation is defined to be a fiscal basket case and employee welfare agency in the US); and that, to a 90% level of accuracy, local consultants and industry professionals, especially the most senior and domestically successful, are both completely ignorant of world class operations (I once spent a couple hours with a very high up NYMTA operations person who had never travelled outside outside the USA beyond a vacation to London and knew at all nothing about any overseas operations, to the extent of no knowing Germany had "commuter trains") and actively hostile to the concept that they don't know best (big fish in very small ponds; rent-seeking; closed, catelised market; ego insecurity; lack of curiosity; disinterest in learning; profitablity of under-achievement.)

Seriously, show up at your next dog and pony public meeting and ask any of the industry zombies to compare and contrast their bizarre There Is No Alternative professionally-justified schemes against any of the dozen overseas examples I'm sure you could rattle off the top of your head. "You don't understand, we're operating under Unique Local Conditions. End of Story."

It's not two freight trains a day that cause people to build parking lots for trains instead of stations for passengers, for example (we're seeing this in San Jose and at two different SF terminals): it's a cultural norm of not caring about operations, not caring about costs, not caring about passengers, and just functioning at the minimum brain-dead level of all the other APTA agencies and US freight lines.

The very ideas that more could be done better with less, or that imitating foreign success might be either desirable or successful, reside in a alien universe and never even enter into the equation. Non-overlapping Magisteria!

Mmmmm.... more concrete! Bigger constuction budgets! More operating employees! Easy to copy plans dating from 1920. Go away, you stinking foreigners and let's do business as usual amongst ourselves.

Re HSR south of Redwood Junction (ie Pacheco) causing operational grief and infrastructure costs north of Redwood City (eg in San Mateo), and going some distance off topic, but since you asked:

Perhaps the simplest way to think of it is that with Altamont HSR there are two classes of traffic on the line, express and local, while given the Pacheco disaster we have to deal with express, local and high speed.

North of Redwood Junction there are a number of fairly closely spaced speed restrictions; in real world operations HS trains will be driven conservatively and similarly to Caltrain between those slowdowns; and the set of HS stops (Millbrae) isn't too dissimilar from the Caltrain express stops (Hillsdale, Millbrae, maybe Mission Bay.)

So for scheduling purposes, which also means for infrastructure purposes, HS trains Redwood City-SF will act very much like Caltrain expresses.

Even more importantly, HS trains never need to overtake Caltrain expresses trains and HS trains overtake at most one Caltrain local, even with a realistic 2 or unlikely 4 Altamont higher speed trains per direction per hour, and even with an unrealistic 4 Caltrain locals + 4 Caltrain expresses per direction per hour.

This is crucial, because delay-free overtakes of stopped trains require several miles of triple/quadruple track, while overtakes of moving trains (eg trying to catch and pass a Caltrain express between stops) require tens of miles of duplicate track.

Lastly, because trains from Altamont-Dumbarton merge into the Caltrain traffic half way along the line and from their own uncongested line, it's possible to buffer train arrivals times as they approach the junction so that they slot in precisely with the heavier Caltrain traffic. (Yes, that can also be done in Gilroy, but then there's another 50 miles in which things can screw up and in which small delays can add up.)

Contrast now with HS trains coming from Los Banos via San Jose.

Here we end up with three classes of traffic: Caltrain local, Caltrain express, and HS. Due to the fewer stops, uncurvy track (straight shot from Mountain View to Redwood City, for example) and longer interaction distance (50 miles vs just over half that), HS trains are going to end up with significantly and qualitatively different schedules from Caltrain.

HS trains are going to have to overtake at least 2 and perhaps 3 Caltrain locals between SJ and SF, with each overtake meaning both expensive, intrusive construction of parallel track and providing potential for delays. Worst, HS trains are going to either catch up to Caltrain expresses, come very close to catching them, and are going to force Caltrain express/local overtakes to happen in additional, non-optimal and expensive locations. (Locations beyond the limited, constructable, multi-purpose and centrally-placed Redwood City-San Mateo overtake which is all Altamont needs for both Caltrain and HSR.)

The best possible Caltrain service pattern, in which local and express trains do same-direction cross-platform transfers in the process of the overtake, becomes infeasible or at best very fragile and prone to disruption of any of the traffic classes.

So we go from an Altamont scenario of comparatively low schedule risk, modest infrastructure requirements, homogenised speeds, Caltrain-rider-friendliness, transfer-richness, fewer traffic classes, fewer interactions between traffic classes, and minimized time-distance exposure of traffic classes to each other, to a Pacheco scenario in which we lose Caltrain transfers, have many more traffic class interactions (overtakes), run the risk of having to make very infrastructure-expensive low-delta-v running overtakes of slightly slower trains by slightly faster ones, and expose more of Caltrain's operations to HS-induced delays and vice versa.

Altamont alignment is actually operationally more restrictive since people with destinations SF/SJ cannot share a train, each train must be separate, or at least the trains will have to stop and decouple sometime before reaching SJ, thus slowing the trip and adding an unnecessary stop for all.

You can't actually be serious in arguing that the Pacheco Pass is better because travelers to SF and SJ can share the same train?!? Is this for the rare instance when a married couple leaves LA, and the husband needs to go San Francisco and the wife needs to go to San Jose??? Going directly to either SF or SJ is better, and of course, the important Bay Area/Sacramento link is still viable with the Altamont Pass. Anyway, forget all this decoupling business. One of the LA-originating travelers could also just switch in Fremont for the Sacramento-San Jose train.